The threat of an antibiotic resistance crisis has revived interest in diverse biological approaches against infectious diseases, including the use of phages against bacterial infections. Due to its malleable genetic character, E. coli has one of the widest spectra of disease of any bacterial species. E. coli phages are commonly isolated from sewage, hospital waste water, polluted rivers and faecal samples of humans or animals. The aim of this study was to isolate phages from human faeces to target multiple E. coli pathotypes.
Seventeen E. coli strains, including representatives of the uropathogenic E. coli (UPEC- UTI), eneterotoxigenic, E. coli (ETEC), enteropathogenic E. coli (EPEC), adherent invasive E. coli (AIEC), enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAggEC or EAEC), were used in the screening study.
Phages were isolated from faeces using two enrichment steps, whereby the faecal material was mixed with multiple- or individual- E. coli strains in Luria Bertani broth (LB) supplemented with CaCl2 and MgSO4, and incubated shaking for 24 h at 37°C.
Following centrifugation and filtration, samples were analysed for the presence of the phages using standard spot and double-layer plaque assay techniques. Of 50 plaques tested we found at least four distinct phage types on the bases of RAPD-PCR and DNA enzymatic restriction profile analysis. The four phages demonstrated broad host range specificity in a spot test, especially against UPEC and AIEC, and we plan to investigate their therapeutic potential for some of the diseases in which these pathotypes are implicated as causative agents.